Motor

ABSTRACT

A motor is provided which can detect a rotor temperature with high precision with a simple configuration not taking an influence on a temperature caused by circulation of a cooling oil into account. In a motor including a rotor, a stator arranged around the rotor, and a temperature sensor, the rotor includes an oil reservoir unit that reserves an oil on a rotating shaft line in an interior thereof, and the temperature sensor detects a temperature of the oil reserved in the oil reservoir unit.

TECHNICAL FIELD

The present invention relates to a motor, and more particularly to amotor that can detect a rotor temperature with high precision.

BACKGROUND ART

In recent years, in a field of transport equipments such as an electricvehicle, a hybrid vehicle, and an electric train, the development of amotor that can achieve a high efficiency and a high torque with areduction in size and weight has been rapidly advanced from theviewpoints of a reduction in an environmental load.

As an example of this motor, there is an IPM motor (interior permanentmagnet motor) in which a magnet is embedded in an interior of a rotor.The IPM motor can use both of a reluctance torque caused bymagnetization of the rotor and a torque caused by magnetization of themagnet, and the magnet is embedded in the interior of the rotor formedof a silicon steel plate. As a result, the magnet does not fall out tothe external by a centrifugal force of the motor even during rotation ofthe motor, and an excellent safety is obtained. For that reason, acurrent phase is controlled to enable high torque operation andoperation at an extensive speed.

Incidentally, in general, there has been known that in an inductionmotor using no magnet, when the motor is driven by an inverter circuit,an iron loss of a rotor is converted into a heat, a temperature of therotor rises, and a motor torque is lessened. In particular, in the caseof the IPM motor in which the magnet is embedded in the interior of themotor, a magnet temperature also rises in association with thetemperature rise of the rotor. When the magnet temperature exceeds alimit temperature, the magnet is demagnetized to further lessen themotor torque. Also, there arises such a problem that even if the magnetthus demagnetized is cooled to return the magnet temperature to thelimit temperature, a desired motor torque is not obtained.

Under the circumstances, in order to suppress a reduction in the torqueof the motor attributable to the rise of the rotor temperature and areduction in the efficiency caused by the torque reduction, there arisesan urgent issue in this field to precisely measure the rotor temperaturewithin the motor, and also the temperature of the magnet when the magnetis embedded in the rotor.

However, because the rotor per se rotates during driving of the motor,it is extremely difficult to measure the temperature of the rotor or themagnet within the rotor, for example, by cable. It is also conceivableto measure the temperature of the rotor, etc. by a non-contactthermometer such as a thermography. However, this makes the deviceconfiguration complicated and upsized, resulting in an increase in themanufacturing costs of the motor.

Under the circumstances, a technique of measuring the rotor temperatureor the magnet temperature with the use of a cooling oil that is reflexedwithin the motor in order to cool the rotor is disclosed in PTL 1 andPTL 2. PTL 1 discloses a rotor temperature estimation method ofmeasuring an inflow temperature of the cooling oil before being suppliedto the rotor and an outflow temperature of the cooling oil after therotor has been cooled, in reflexing the cooling oil within the motor,and estimating the rotor temperature on the basis of the inflowtemperature, the outflow temperature, a thermal resistance of the rotorwhich has been obtained in advance, and a weight corresponding to anoperating status of the rotor.

Also, PTL 2 discloses a magnet temperature estimation device and amethod therefor, which estimate the magnet temperature by directlymeasuring the temperature of the cooling oil after the magnet has beencooled, which is emitted by a centrifugal force when rotationallydriving the rotor.

-   PTL 1: JP-A-2000-23421-   PTL 2: JP-A-2008-178243

SUMMARY OF INVENTION Technical Problem

In the rotor temperature estimation method disclosed in PTL 1, becausethe rotor temperature or the magnetic temperature is estimated with theuse of an arithmetic expression defined in advance, the operation ofconstructing a variable for the arithmetic operation is required. Also,in order to make an estimated value of the rotor temperature or themagnetic temperature, which is calculated according to the abovearithmetic expression, approximate to a real temperature of the rotor orthe magnet, there is a need to detect the states of the cooling oil suchas the flow rate or flow velocity of the cooling oil, the inflowtemperature of the cooling oil into the rotor, or the outflowtemperature of the cooling oil from the rotor, with high precision.

Also, in the magnet temperature estimation device and the methodtherefor disclosed in PTL 2, the cooling oil temperature to be measuredis changed by the flow rate of the cooling oil or the inflow temperatureof the cooling oil into the rotor. For that reason, the rotortemperature or the magnet temperature to be estimated cannot be made toapproximate to the real temperature without a complicated calculationtaking the flow rate and the inflow temperature into account.

Thus, in both of the rotor temperature estimation methods disclosed inPTL 1 and PTL 2, there is a need to accurately grasp a circulation stateof the cooling oil subjected to forced convection such as the flowvelocity or the flow rate, and the temperature change when the coolingoil passes through the rotor. However, it is difficult to detect thestate of the cooling oil with elaboration. Therefore, the rotortemperature or the magnet temperature cannot be measured with highprecision.

The present invention has been made in view of the above problems, andan object of the present invention is to provide a motor that can detectthe rotor temperature with high precision with a simple configurationnot taking an influence on the temperature caused by the circulation ofthe cooling oil into account.

Solution to Problem

In order to solve the above problem, according to the present invention,there is provided a motor, including a rotor, a stator arranged aroundthe rotor, and a temperature sensor, in which the rotor includes an oilreservoir unit that reserves an oil on a rotating shaft line in aninterior thereof, and the temperature sensor detects a temperature ofthe oil reserved in the oil reservoir unit.

According to the above configuration, since the rotor includes the oilreservoir unit for reserving the oil on the rotating shaft line, thereserved oil temperature can be detected by the temperature sensor, anda rotor temperature can be detected according to the oil temperature. Asa result, the rotor temperature can be detected with high precision nottaking an influence of an inflow temperature, the flow rate, and theflow velocity of the oil into account.

Advantageous Effects of Invention

As understandable from the above description, according to the presentinvention, the rotor temperature can be easily detected with highprecision by measuring a temperature of a fluid reserved in thereservoir unit within the rotor. In particular, in the case of a magnetmotor in which a magnet is embedded within the rotor, a magnettemperature can be also calculated with high precision with the use ofthe detected rotor temperature, and the demagnetization of the magnetattributable to the temperature rise can be effectively suppressed.

The other problems, configurations and advantageous effects will becomeapparent from the following description of the embodiments.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical cross-sectional view illustrating a motor accordingto a first embodiment of the present invention.

FIG. 2 is an enlarged diagram of an oil reservoir unit according to thefirst embodiment illustrated in FIG. 1, in which (a) shows a verticalcross-sectional view illustrating a relationship between an oil and atemperature sensor in a motor stop state, (b) shows a view taken alongan arrow A-A of (a), (c) shows a vertical cross-sectional viewillustrating a relationship between the oil and the temperature sensorin a motor drive state, and (d) shows a view taken along an arrow C-C of(c).

FIG. 3 is a, vertical cross-sectional view illustrating a motoraccording to a second embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view illustrating a motor accordingto a third embodiment of the present invention.

FIG. 5 is an enlarged diagram of an oil reservoir unit according to athird embodiment of the present invention, in which (a) shows a verticalcross-sectional view illustrating a relationship of an oil, atemperature sensor, and a continuous hole in a motor stop state, and (b)is a vertical cross-sectional view illustrating a relationship of theoil, the temperature sensor, and the continuous hole in a motor drivestate.

FIG. 6 is a vertical cross-sectional view illustrating a motor accordingto a fourth embodiment of the present invention.

LIST OF REFERENCE SIGNS

-   -   1, rotor    -   2, stator    -   3, coil    -   4, oil reservoir unit    -   6, oil seal    -   7, step    -   8, 19, oil supply path    -   9, magnet    -   10, gear    -   11, oil inflow path    -   12, inflow port    -   13, oil outflow path    -   14, outflow port    -   15, coupling path    -   16, continuous hole    -   17, partition    -   18, oil circulation path    -   19A, oil exhaust path    -   20, 60, motor cover    -   21, outside cap    -   22, inside cap    -   23, 63, bearing    -   24, inverter circuit    -   25, 65, rotating angle sensor    -   26, rotation control means    -   27, temperature calculation unit    -   28, substrate    -   29, 68, opening portion    -   30, temperature sensor    -   31, cylindrical portion    -   32, bottom portion    -   33, jaw portion    -   34, corner portion    -   35, housing    -   36, temperature detection unit    -   40, reducer    -   41, housing    -   42, oil storage chamber    -   43, gear    -   44, shaft    -   45, bearing    -   46, oil seal    -   47, oil pool    -   48, oil supply path,    -   51, motor case    -   52, water jacket    -   53, bearing    -   54, step    -   61, 62, oil seal    -   64, oil storage unit    -   69, oil exhaust path    -   100, 200, 300, 400, motor    -   A, continuous hole inner diameter    -   D, oil reservoir unit inner diameter    -   d, temperature sensor outer diameter    -   L, rotor rotating shaft line    -   P, PA, oil

DESCRIPTION OF EMBODIMENTS

Hereinafter, a motor according to embodiments of the present inventionwill described with reference to the drawings.

First Embodiment

FIG. 1 illustrates a motor according to a first embodiment of thepresent invention. In the first embodiment, a configuration in which amagnet is embedded in an interior of a rotor will be described. However,the same configuration can be applied to a configuration in which nomagnet is embedded in the interior of the rotor.

A motor 100 shown in the figure includes a rotor 1 and a stator 2arranged around an outer peripheral surface lA of the rotor 1, and acoil 3 is wound on the stator 2 in multiple turns, and the coil 3 isenergized so that the rotor 1 is rotationally driven about a rotatingshaft line L as a rotating center. A magnet 9 is embedded in an interiorof the rotor 1 along the outer peripheral surface 1A thereof.

Also, a motor case 51 internally having a water jacket 52 whichcirculates a cooling water is disposed outside of the stator 2. Withthis configuration, an outer peripheral surface of the rotor 1 and thestator 2 can be protected from an external environment, and a heatradiated from the rotor 1 can be absorbed by the internal cooling waterto cool the rotor 1 or the stator 2. Also, a motor cover 20 including anoutside cap 21 and an inside cap 22 is disposed on one end side of therotor 1 in the rotating shaft line L direction. A substrate 28 isdisposed on a surface 22A of the inside cap 22 of the motor cover 20facing the outside cap 21, and an inverter circuit 24 having atemperature calculation unit 27 that calculates a rotor temperature anda magnet temperature is placed on the substrate 28. The inverter circuit24 further includes a rotation control unit 26 so as to control arotating speed of the rotor 1 on the basis of a signal from a rotatingangle sensor 25 disposed on the rotor 1 side of the inside cap 22 inorder to detect the rotation of the rotor 1 and the rotor temperatureand the magnet temperature calculated by the temperature calculationunit 27. Also, bearings 53 and 23 are disposed between the motor case 51and the rotor 1, and between the inside cap 22 and the rotor 1,respectively, so that the rotor 1 can rotate relatively with respect tothe motor case 51 and the inside cap 22.

An oil reservoir unit 4 for reserving an oil P on the rotating shaftline L of the rotor 1 is disposed on an end of the motor cover 20 sideof the rotor 1. In this example, the oil reservoir unit 4 is formed intosubstantially a cylindrical shape coaxial with the rotating shaft line Lof the rotor 1. Also, an opening portion 29 is formed substantially inthe center (on the rotating shaft line L of the rotor 1) of the insidecap 22 of the motor cover 20. A temperature sensor 30 is insertedthrough the opening portion 29 along the rotating shaft line L, andfitted to the inside cap 22 by a jaw portion 33. The jaw portion 33 ofthe temperature sensor 30 is fixedly engaged with an outer peripheralportion of the opening portion 29 of the inside cap 22 so that thetemperature sensor 30 is fixed to the inside cap 22. In this example,the temperature sensor 30 is formed into the substantially cylindricalshape coaxial with the rotating shaft line L of the rotor 1, as with theoil reservoir unit 4. As described above, the temperature sensor 30 isinserted along the rotating shaft line L, and fitted to the inside cap22 by the jaw portion 33, as a result of which the entire temperaturesensor 30 is inserted into the oil reservoir unit 4 along the rotatingshaft line L without contact with the rotor 1. An outer diameter of thetemperature sensor 30 is set to be relatively smaller than an innerdiameter of the oil reservoir unit 4. As described above, thetemperature sensor 30 formed into the substantially cylindrical shape onthe rotating shaft line L of the rotor 1 is arranged without contactwith an inner surface of the oil reservoir unit 4 having thesubstantially cylindrical shape. As a result, even if the rotor 1rotates around the temperature sensor 30 in a state where thetemperature sensor 30 is fixed to the motor cover 20, an innerperipheral surface of the oil reservoir unit 4 and an outer peripheralsurface of the temperature sensor 30 do not contact with each other, andare not worn away.

Also, the oil P of a given amount is reserved in the oil reservoir unit4, and the temperature sensor 30 and the oil P come indirect contactwith each other at the time of stopping or driving the motor, and a heatis transmitted between the temperature sensor 30 and the rotor 1 throughthe oil P. That is, the heat radiated from the rotor 1 is transmitted tothe oil P, and further transmitted to the temperature sensor 30 so thatthe temperature of the oil P is measured by the temperature sensor 30 todetect the temperature of the rotor 1. An oil seal 6 is interposedbetween the rotor 1 and the temperature sensor 30, and as shown in thefigure, the temperature sensor 30 is fixed to the motor cover 20. Evenif the rotor 1 rotates relatively with respect to the temperature sensor30, the oil seal 6 can prevent the oil P within the oil reservoir unit 4from being leaked out of the rotor 1.

The temperature sensor 30 is roughly configured by a housing 35including a cylindrical portion 31 extending in the rotating shaft lineL direction of the rotor 1 and a bottom portion 32 that closes one endof the cylindrical portion 31, and a temperature detection portion 36.The temperature detection portion 36 is fitted to the inner peripheralsurface of the cylindrical portion 31, and an end of the housing 35opposite to the bottom portion 32 is opened, and the temperaturedetection portion 36 is joined to the inverter circuit 24 through anopening portion of the opposite end by a conductive wire not shown. As aresult, a detected signal of the temperature of the oil P, which ismeasured by the temperature detection portion 36, is transmitted to thetemperature calculation unit 27 and the rotation control unit 26 withinthe inverter circuit 24, and used for calculation of the temperatures ofthe rotor 1 and the magnet 9, or for control of the rotating speed ofthe rotor 1. The temperature sensor 30 is formed into the cylindricalshape, and the temperature detection portion 36 is arranged insidethereof so that the temperature detection portion 36 and the oil P to bemeasured can be arranged in proximity to each other, and the temperaturemeasurement with a high response and higher elaboration is enabled. Thetemperature detection portion 36 may be, for example, a thermistor or athermocouple.

A reducer 40 is disposed on a side of the motor case 51 opposite to themotor cover 20 side. The reducer 40 is roughly configured by a housing41 that demarcates an oil storage chamber 42, and a gear 43 that isdisposed on a shaft 44 arranged within the housing 41. A gear 10disposed on the end of the rotor 1 and the gear 43 are meshed with eachother so that the rotating speed of the rotor 1 is reduced andtransmitted to the shaft 44. A bearing 45 is disposed between thehousing 41 and the shaft 44 so that the shaft 44 can rotate relativelywith respect to the housing 41.

Subsequently, a procedure of assembling the motor 100 according to thefirst embodiment will be described.

First, the rotor 1 in which the magnet 9 is embedded along the outerperipheral surface 1A, and the stator 2 on which the coil 3 is wound areprepared. Also, the motor case 51 having the water jacket 52, and thebearing 53 fitted to the end opposite to the side to which the motorcover 20 is fitted is prepared. Then, the stator 2 is inserted into themotor case 51 from the side at which the motor cover 20 is fitted. Inthis situation, a step 54 formed on the inner peripheral surface of themotor case 51 is abutted against a corner of the stator 2 to positionthe stator 2 relative to the motor case 51. Then, the rotor 1 isinserted into the motor case 51 until a step 7 formed on the rotor 1 isabutted against the bearing 53.

Also, the motor cover 20 is prepared in another process different fromthe above process. That is, the substrate 28 is fitted to one surface22A of the inside cap 22 of the motor cover 20, and the inverter circuit24 having the temperature calculation unit 27 and the rotation controlunit 26 is placed on the substrate 28. Also, the rotation sensor 25 andthe bearing 23 are arranged on the other surface opposite to the onesurface 22A of the inside cap 22. The opening portion 29 is formedsubstantially in the center of the inside cap 22, and the temperaturesensor 30 is inserted through the opening portion 29 in the rotatingshaft line L direction of the rotor 1, and fitted to the inside cap 22by the jaw portion 33 on the end thereof. The rotation sensor 25 and thetemperature sensor 30 are connected to the inverter circuit 24 by aconductive wire not shown. The outside cap 21 is fitted to the insidecap 22 so as to cover the one surface 22A of the inside cap 22, that is,the inverter circuit 24 to form the motor cover 20. As a method offitting the outside cap 21 and the inside cap 22, there are a fittingmethod using a fitting claw, a fitting method using a fastening membersuch as a bolt or a screw, and a fitting method due to adhesion by usingan adhesive.

After the motor cover 20 is thus installed, and the oil P of the desiredamount is poured into the oil reservoir unit 4 of the rotor 1, the motorcover 20 is fitted to the motor case 51 along the rotating shaft line Lso that a part of the temperature sensor 30 of the motor cover 20 isinserted into the oil reservoir unit 4. A corner 34 of a leading end ofthe temperature sensor 30 is tapered so that the temperature sensor 30can be guided into the oil reservoir unit 4. Also, the oil seal 6 isarranged between the rotor 1 and the temperature sensor 30 on an end ofthe oil reservoir unit 4 of the rotor 1 so that the oil P is not leakedout of the rotor 1 from the oil reservoir unit 4 after the temperaturesensor 30 is inserted into the oil reservoir unit 4.

FIG. 2 illustrates a relationship between the oil P poured into the oilreservoir unit 4 and the temperature sensor 30 according to the firstembodiment. FIG. 2( a) illustrates a motor stop state, FIG. 2( b) is aview taken along an arrow A-A of FIG. 2( a), FIG. 2( c) illustrates amotor drive state, and FIG. 2( d) is a view taken along an arrow C-C ofFIG. 2( c). In general, when the motor 100 of the first embodiment isapplied to a vehicle, as illustrated in FIGS. 1 and 2, the motor 100 isfitted to the vehicle so that the rotating shaft line L of the rotor 1becomes horizontal.

As illustrated in FIG. 2( a), when the motor 100 is arranged in thevehicle so that the rotating shaft line L of the rotor 1 becomeshorizontal, the oil P pools in a lower portion of the oil reservoir unit4 in the stop state of the motor 100. Even in the stop state of themotor 100, in order to detect the temperature of the rotor 1 by thetemperature sensor 30, as illustrated in FIG. 2( b), there is a need toreserve the oil P in the oil reservoir unit 4 by the amount of oil Prequired to transmit the heat between the temperature sensor 30 and therotor 1, that is, so that a space between a lower portion of the oilreservoir unit 4 of the rotor 1 and a lower portion (temperaturedetection portion 36) of the temperature sensor 30 is filled with theoil P.

As illustrated in FIG. 2( c), when the motor 100 is driven, the oil P inthe oil reservoir unit 4 is thrust outside of the oil reservoir unit 4in the radial direction by its centrifugal force, and a (heattransmission) layer of the oil P is formed on the inner peripheralsurface of the oil reservoir unit 4. In order to detect the temperatureof the rotor 1 by the temperature sensor 30 with high precision in theabove drive state of the motor 100, as illustrated in FIG. 2( d), thereis a need to reserve the oil P by the amount as large as the spacebetween the rotor 1 and the temperature sensor 30 is filled with thelayer of the oil P, that is, by the amount of π(D²−d²)L1/4 or more. Inthis expression, D is an inner diameter of the oil reservoir unit 4, dis an outer diameter of the temperature sensor 30, and L1 is a length ofthe oil reservoir unit 4 in the rotating shaft line L. When the rotatingspeed of the rotor 1 is relatively low in the drive state of the motor100, because the oil P in the oil reservoir unit 4 pools on the lowerportion, the amount of oil P reserved in the oil reservoir unit 4 can bereduced.

As described above, the oil P is thrust outside in the radial directionat the time of driving the motor 100. Therefore, even in this case, inorder to measure the temperature of the oil P by the temperaturedetection portion 36 of the temperature sensor 30 with a high responseand elaboration, as illustrated in FIG. 2, it is preferable that thetemperature detection portion 36 is fitted to the outside in the radialdirection with respect to the rotating shaft line L of the rotor 1, thatis, on the inner peripheral surface of the cylindrical portion 31 of thetemperature sensor 30.

In the above first embodiment, the temperature detection portion 36 ofthe temperature sensor 30 is fitted to particularly the lower side ofthe inner peripheral surface of the cylindrical portion 31. With theabove configuration, even when the motor 100 is arranged so that therotating shaft line L of the rotor 1 becomes horizontal, and in the stopstate of the motor 100 as illustrated in FIG. 2( a), the heat is alwaystransmitted between the inner peripheral surface of a portion to whichthe temperature detection portion 36 is fitted, and the rotor 1 throughthe oil P, and the temperature of the oil P can be measured by thetemperature detection portion 36 with the high response. Also, even whenthe rotating speed of the rotor 1 is low, because the oil P within theoil reservoir unit 4 mainly pools in a vertically lower portion, it ispreferable that the temperature detection portion 36 is fitted to thelower side of the inner peripheral surface of the cylindrical portion 31of the temperature sensor 30. That is, the temperature detection portion36 is fitted to the vertically lower side of the inner peripheralsurface of the cylindrical portion 31 of the temperature sensor 30 as inthe first embodiment. As a result, the heat of the rotor 1 can beefficiently transmitted to the temperature detection portion 36regardless of the rotating speed of the rotor 1, and the heattransmission characteristic from the rotor 1 can be stabilized.

When the rotating shaft line L of the rotor 1 becomes vertical, that is,the motor cover 20 is arranged on a vertically upper portion, the oil Ppools at the end of the oil reservoir unit 4 opposite to the motor cover20 side at the time of stopping the motor 100. For that reason, in orderto transmit the heat between the rotor 1 and the temperature sensor 30,there is a need to reserve the oil P within the oil reservoir unit 4 bythe amount of πD² (L1−L2)/4 or more. In this expression, L2 is a lengthof the temperature sensor 30 in the oil reservoir unit 4 in the rotatingshaft line L direction. On the other hand, when the rotor 1 rotates at arelatively high speed, as in FIG. 2( c) and (d), the oil P is thrustoutside in the radial direction of the oil reservoir unit, it ispreferable to reserve the oil P by the amount of π(D²−d²)L1/4 or more.Also, when the motor cover 20 is arranged on the vertically upperportion as described, in order to measure the temperature of the oil Pwith a high response, particularly at the time of stopping the motor100, the temperature detection portion 36 can be disposed on the innersurface of the bottom portion 32 of the temperature sensor 30.

Also, when the overall oil reservoir unit 4 is filled with the oil P, acontact area of the temperature detection unit 30 and the oil P canincrease, and the oil P temperature can be more efficiently measured bythe temperature detection portion 36. Also, when the overall oilreservoir unit 4 is filled with the oil P, even if the rotating shaftline L of the rotor 1 is arranged to be horizontal or vertical, thetemperature of the oil P can be measured with high precision regardlessof the mounting position of the temperature detection portion 36 and therotating speed of the rotor 1.

Thus, in the first embodiment, in measuring the temperature of the oilto which the heat is transmitted from the rotor 1 by the temperaturedetection portion 36, when the temperature of the oil P reserved in theoil reservoir unit 4 is measured, the temperature of the oil P can bemeasured without taking the influence of the inflow temperature, theflow rate, and the flow velocity of the oil P into account. On the basisof the measurement result, the temperature of the rotor 1 can bedetected with high precision. In detecting the temperature of the rotor1, calibration information on the temperature of the oil P and thetemperature of the rotor 1 which are obtained in advance may be used.Also, the temperature of the magnet 9 which is embedded in the rotor 1whose temperature can generally become higher than those temperaturescan be calculated with high precision by using the temperaturecalculation unit 27 on the basis of the drive state (rotor rotatingspeed and torque) of the motor, an energy loss (iron loss) correspondingto the drive state, a heat resistance and a heat capacity of the rotor 1which are obtained in advance. The rotation of the rotor 1 can becontrolled with elaboration by the rotation control unit 26 on the basisof those calculated temperatures so that the rotor temperature and themagnet temperature do not exceed the limit temperature. As a result, thehigher efficiency and the higher torque of the motor 100 can berealized.

Second Embodiment

Subsequently, a description will be given in detail of a motor accordingto a second embodiment of the present invention with reference to FIG.3. In the figure, the same configurations as those in the firstembodiment are denoted by identical symbols, and their detaileddescription will be omitted.

A motor 200 according to the second embodiment is different from that ofthe first embodiment in that the rotor 1 provides an oil supply path 8extending from a bottom of the oil reservoir unit 4 to the end of therotor 1 at the reducer 40 side along the rotating shaft line L. Also,the housing 41 forms an oil supply path 48, and the oil supply path 48communicates between an oil pool 47 demarcated by the end of the rotor 1and the housing 41, and the oil storage chamber 42 so that the oilwithin the oil storage chamber 42 can flow into the oil supply path 8through the oil pool 47. An oil seal 46 is provided between the rotor 1and the housing 41 so that the oil in the oil pool 47 is not leaked intothe oil storage chamber 42.

In the second embodiment, unlike the first embodiment, when the motorcover 20 is fitted to the motor case 51, there is no need to pour theoil P into the oil reservoir unit 4 in advance. That is, when the motorcover 20 is fitted to the motor case 51, a part of the temperaturesensor 30 is inserted into the oil reservoir unit 4 in a state where theoil P is not reserved in the oil reservoir unit 4. Then, after the motorcover 20 and the reducer 40 are fitted to the motor case 20, the coil 3of the motor 200 is energized to rotate the rotor 1 at a desiredrotating speed, and rotate the shaft 44 of the reducer 40. As a result,the oil P reserved in the oil storage chamber 42 of the housing 41 isdiffused to and flows into the oil supply path 48. The oil P that hasflowed into the oil supply path 48 is supplied to the oil supply path 8of the rotor 1 through the oil pool 47. Further, the oil P is suppliedto the oil reservoir unit 4 that fluidically communicates with the oilsupply path 8. For example, an on-off valve (not shown) is provided inthe oil supply path 48, and after the oil P of a desired amount isreserved in the oil reservoir unit 4, the on-off valve may be closed tostop the supply of the oil. Also, a height of a top of the oil supplypath 48 formed in the housing 41 in the vertical direction is set to berelatively higher than a height of the oil reservoir unit 4 in thevertical direction, thereby being capable of surely supplying the oil P,to the oil reservoir unit 4 of the rotor 1. Also, in the secondembodiment, even if the oil P in the oil reservoir unit 4 is leaked fromthe oil seal 6, the oil reservoir unit 4 is replenished with the oil Pthrough the oil supply path 8 so that the oil P of a desired amount canbe reserved in the oil reservoir unit 4. When the oil P of a givenamount or more is reserved in the oil reservoir unit 4, an oil pressurein the oil supply path 8 is adjusted so that the oil P can be dischargedfrom the oil reservoir unit 4 to the oil supply path 8.

Third Embodiment

Subsequently, a description will be given in detail of a motor accordingto a third embodiment of the present invention with reference to FIG. 4.In the figure, the same configurations as those in the first and secondembodiments are denoted by identical symbols, and their detaileddescription will be omitted.

A motor 300 according to the third embodiment is different from themotor 200 of the second embodiment in that the oil supply path 8includes an oil inflow path 11 and an oil outflow path 13, and alsodifferent from the motor 100 of the first embodiment in that there isprovided an oil circulation path 18 mainly including the oil inflow path11 and the oil outflow path 13 in the interior of the rotor 1, and theoil storage chamber 42 and the oil supply path 48 within the housing 41.The oil P high in thermal conductivity reserved in the oil storagechamber 42 is circulated in the interior of the oil circulation path 18so that the heat radiation from the rotor 1 can be sucked to cool therotor 1. As the lengths of the oil reservoir unit 4 and the temperaturesensor 30 in the direction of the rotating shaft line L are longer, thetemperature of the rotor 1 can be detected with higher precision. In themotor 300 according to the third embodiment, in order to ensure the oilcirculation path 18, the lengths of the oil reservoir unit 4 and thetemperature sensor 30 in the direction of the rotating shaft line L arerelatively short as compared with those in the first and secondembodiments.

The above oil circulation path 18 will be described in detail. First,when the coil 3 of the motor 300 is energized to rotate the rotor 1 andthe shaft 44, the oil reserved within the oil storage chamber 42 isdiffused to and flows in the oil supply path 48. Thereafter, the oilpasses through the oil pool 47, and flows into the oil inflow path 11through an inflow port 12 formed in the end of the rotor 1. The oilwithin the oil inflow path 11 mainly flows in the direction of therotating shaft line L of the rotor 1, passes through a coupling path 15in the radial direction which is provided in the vicinity of theopposite end of the oil inflow path 11, and flows outside of the oilinflow path 11 in the radial direction. The oil outflow path 13fluidically communicated with the coupling path 15 is disposed outsideof the oil inflow path 11 in the radial direction. The oil that hasflowed into the coupling path 15 flows in the interior of the oiloutflow path 13 in the rotating shaft line L direction (directionopposite to the inflow direction) of the rotor 1. Then, the oil isdischarged into the oil storage chamber 42 through an outflow port 14formed in the end of the oil outflow path 13. The oil circulation path18 of the oil P for rotor cooling is thus formed. The oil circulationpath 18 absorbs the heat of the rotor 1 while the oil P is passingthrough the oil inflow path 11, the oil outflow path 13, and thecoupling path 15, and the heat radiated from the rotor 1 is radiated tothe external of the motor 300. As illustrated in the figure, since theoil outflow path 13 is disposed outside of the oil inflow path 11 in theradial direction, the heat radiated from the rotor 1 is mainly absorbedby the oil within the oil outflow path 13, and the oil can be rapidlydischarged to the outside of the rotor 1. As a result, the rotor 1 canbe efficiently cooled.

The oil inflow path 11 and the oil outflow path 13 in the oilcirculation path 18 is isolated from the oil reservoir unit 4 by apartition 17. However, a continuous hole 16 is pierced substantially inthe center (on the rotating shaft line L of the rotor 1) of thepartition 17, and the oil inflow path 11 and the oil reservoir unit 4fluidically communicate with each other through the continuous hole 16.With the provision of the continuous hole 16, a part of the oil Pflowing in the oil inflow path 11 can be supplied to the oil reservoirunit 4 through the continuous hole 16, and the oil P in the oilreservoir unit 4 can be discharged to the oil inflow path 11 through thecontinuous hole 16.

Since a part of the oil P flowing in the oil circulation path 18 is thussupplied to the oil reservoir unit 4 through the continuous hole 16,there is no need to pour the oil P into the oil reservoir unit 4 inadvance in the third embodiment, as in the second embodiment. That is,in an initial stage where the oil P is circuited in the oil circulationpath 18, the coil 3 of the motor 300 is energized to rotate the rotor 1at a desired rotating speed so that the oil P in the oil storage chamber42 can be supplied to the oil reservoir unit 4. In order to efficientlysupply the oil P to the oil reservoir unit 4, a spiral groove (notshown) may be formed in a part of the oil inflow path 11 or the innerperipheral surface of the continuous hole 16 in advance, and the oil Pmay be guided to the oil reservoir unit 4. Also, an on-off valve (notshown) may be provided in the oil outflow path 13 or the coupling path15, and the on-off valve may be closed to close the oil outflow path 13or the coupling path 15 until the oil P of a desired amount is reservedin the oil reservoir unit 4, and thereafter the on-off valve may beopened to circulate the oil P in the oil circulation path 18. Also, inthe third embodiment, as in the second embodiment, even if the oil P inthe oil reservoir unit 4 is leaked from the oil seal 6, the oilreservoir unit 4 can be replenished with a part of the oil thatcirculates in the oil circulation path 18 through the continuous hole16. As a result, the oil P of a desired amount can be reserved in theoil reservoir unit 4.

FIG. 5 illustrates a relationship between the oil P poured into the oilreservoir unit 4 and the temperature sensor 30 according to the thirdembodiment. FIG. 5( a) illustrates the motor stop state, and FIG. 5( b)illustrates the motor drive state.

As illustrated in FIG. 5( a), when the motor 300 is arranged in thevehicle so that the rotating shaft line L of the rotor 1 becomeshorizontal, in the stop state of the motor 300, the oil P pools in thelower side of the oil reservoir unit 4. In the third embodiment, withthe provision of the continuous hole 16, if the oil P is supplied to theoil reservoir unit 4 by an amount larger than a given amount, andreserved at a position higher than a height of the continuous hole 16,unnecessary oil P which is reserved at the position higher than thecontinuous hole 16 can be discharged to the oil inflow path 11 throughthe continuous hole 16. Thus, in the third embodiment, a height of theoil P reserved in the oil reservoir unit 4 can be limited to be lowerthan that of the continuous hole 16 to optimize the amount of oil P inthe oil reservoir unit 4. In order to reserve the oil P of the amount aslarge as possible within the oil reservoir unit 4, and transmit the heatbetween the rotor 1 and the temperature sensor 30 through the oil P, forexample, at the time of driving the motor 300, it is preferable todecrease an inner diameter A of the continuous hole 16 as much aspossible. The pressure of the oil flowing in the oil inflow path 11 isadjusted so that the oil P in the oil reservoir unit 4 can be reservedup to a position higher than that of continuous hole 16.

As in the third embodiment, when the continuous hole 16 is formedbetween the oil reservoir unit 4 and the oil inflow path 11, if themotor 300 is arranged in the vehicle so that the rotating shaft line Lbecomes vertical, that is, the motor cover 20 is disposed at thevertically upper portion, there is a possibility that the oil P reservedon the end (vertically lower portion) of the oil reservoir unit 4opposite to the motor cover 20 side is discharged to the oil inflow path11 through the continuous hole 16. For that reason, in the thirdembodiment, it is preferable that the motor 300 is arranged in thevehicle so that the rotating shaft line L of the rotor 1 becomeshorizontal. If the motor 300 is arranged so that the rotating shaft lineL of the rotor 1 becomes vertical, the oil pressure in the oil inflowpath 11 is adjusted, for example, a one-way valve may be provided in thecontinuous hole 16 so as to suppress the discharge of the oil P to theoil inflow path 11.

As illustrated in FIG. 5( b), when the motor 300 is driven, the oil P inthe oil reservoir unit 4 is thrust outside of the oil reservoir unit 4in the radial direction by its centrifugal force, and a layer of the oilP is formed on the inner peripheral surface of the oil reservoir unit 4.Even in this state, in order to detect the temperature of the rotor 1 bythe temperature sensor 30 with high precision, as in the firstembodiment, there is a need to reserve the oil P in the oil reservoirunit 4 by the amount of π(D²−d²)L1/4 or more.

Thus, in the third embodiment, a part of the oil P that circulates forcooling the rotor 1 is reserved in the oil reservoir unit 4, and thetemperature of the rotor 1 can be detected through the reserved oil P.As a result, the influence attributable to the circulation state such asthe inflow temperature, the flow rate, or the flow velocity of thecirculating oil P can be suppressed to detect the temperature of therotor 1 with high precision. Also, because the oil P can be reserved inthe oil reservoir unit 4 with the use of the circulating oil P, aprocess of pouring the oil P into the oil reservoir unit 4 from theexternal in advance becomes unnecessary, and the manufacturing processof the motor can be simplified.

Fourth Embodiment

Subsequently, a description will be given in detail of a motor accordingto a fourth embodiment of the present invention with reference to FIG.4. In the figure, the same configurations as those in the first to thirdembodiments are denoted by identical symbols, and their detaileddescription will be omitted.

FIG. 6 illustrates an embodiment when a lubricating oil high in thethermal conductivity for cooling the bearing is used as the oil P whichis reserved in the oil reservoir unit 4.

The above lubricating oil P flows in an oil supply path 19 providedalong the rotating shaft line L of the rotor 1 from one end of the rotor1, passes through an oil discharge path 19A disposed in the vicinity ofthe end of the oil reservoir unit 4 side and extending in the radialdirection, and is transmitted to an oil storage unit 64 demarcated by aninner surface 60A of a motor cover 60, the rotor 1, and oil seals 61,62. A bearing 63 fitted to the inner surface 60A of the motor cover 60is accommodated in the oil storage unit 64, and the bearing 63 is cooledby an oil PA within the oil storage unit 64. Also, the oil PA thatabsorbs the heat of the bearing 63 and reaches a high temperature passesthrough an oil discharge path 69 formed in the interior of the motorcover 60, and is discharged to the external of a motor 400. Thelubricating oil is supplied from an oil storage chamber for thelubricating oil not shown to the oil supply path 19.

As in the first embodiment, a rotating angle sensor 65 is fitted to theinner surface 60A of the motor cover 60, and connected to rotationcontrol means not shown so as to control the rotating speed of the rotor1. Also, an opening portion 68 is formed substantially in the center (onthe rotating shaft line L of the rotor 1) of the motor cover 60, and thetemperature sensor 30 is attached to pass through the opening portion68.

In this example, the partition 17 is disposed between the oil supplypath 19 and the oil reservoir unit 4 as in the third embodiment, and thecontinuous hole 16 is formed substantially in the center of thepartition 17 so that a part of the oil P flowing in the oil supply path19 is supplied to the oil reservoir unit 4.

In the fourth embodiment, as in the third embodiment, when the motorcover 60 is fitted to the motor case 51, there is no need to pour theoil P into the oil reservoir unit 4 in advance. That is, after the motorcover 60 is fitted to the motor case 51, the rotor 1 is rotated at adesired rotating speed so that a part of the oil P flowing in the oilsupply path 19 can be supplied to the oil reservoir unit 4 through thecontinuous hole 16.

The four embodiments of the present invention have been described above.However, the present invention is not limited to the above embodiments,but can be variously modified in design without departing from thespirit of the invention disclosed in the claims.

As understandable from the above description, according to the first tofourth embodiments, the rotor temperature can be detected through theoil which is reserved in the oil reservoir unit. That is, because thereis no need to consider the influence of the inflow temperature, the flowrate, and the flow velocity of the oil in measuring the oil temperaturereserved in the oil reservoir unit, the rotor temperature can bedetected with easy and high precision on the basis of the abovemeasurement result. Further, when the magnet is embedded within therotor, because the magnet temperature can be calculated with highprecision on the basis of the detected rotor temperature, the rotatingspeed of the rotor can be controlled to suppress the demagnetization ofthe magnet. As a result, the motor can be driven with a high torque anda high efficiency for a long duration.

The present invention is not limited to the above first to fourthembodiments, but includes a variety of modified examples. For example,the above first to fourth embodiments are described in detail forfacilitation to understand the present invention, and the presentinvention does not always provide all of the configurations describedabove. Also, a part of one configuration example can be replaced withanother configuration example, and the configuration of one embodimentcan be added with the configuration of another embodiment. Also, in apart of the respective first to fourth embodiments, anotherconfiguration can be added, deleted, or replaced.

Also, control lines and information lines necessary for description areillustrated, and all of the control lines and the information linesnecessary for products are not illustrated. In fact, it may beconceivable that most of the configurations are connected to each other.

1. A motor comprising: a rotor, a stator arranged around the rotor, anda temperature sensor, wherein the rotor includes an oil reservoir unitthat reserves an oil on a rotating shaft line in an interior thereof,and wherein the temperature sensor detects a temperature of the oilreserved in the oil reservoir unit.
 2. The motor according to claim 1,wherein the temperature sensor has one end fitted to a motor cover ofthe motor, and the other end inserted into the oil reservoir unit on therotating shaft line of the rotor, and contacting with the oil.
 3. Themotor according to claim 1, wherein the temperature sensor includes ahousing having a cylindrical portion and a bottom portion, and atemperature detection unit arranged on an inner peripheral surface ofthe cylindrical portion.
 4. The motor according to claim 2, wherein anoil seal that prevents the oil reserved in the oil reservoir unit frombeing leaked out of the rotor is arranged between the temperature sensorand the rotor.
 5. The motor according to claim 3, wherein thetemperature detection unit is arranged on the inner peripheral surfaceof the cylindrical portion on a lower side of the motor.
 6. The motoraccording to claim 1, wherein the motor includes an oil storage chamber,the rotor includes an oil supply path on the rotating shaft line in aninterior thereof, and the oil storage chamber and the oil reservoir unitcommunicate with each other through the oil supply path.
 7. The motoraccording to claim 6, wherein the oil supply path includes an oilcirculation path having at least an oil inflow path and an oil outflowpath.
 8. The motor according to claim 7, wherein the rotor includes acontinuous hole that communicates between the oil circulation path andthe oil reservoir unit, and the continuous hole is pierced in therotating shaft line.
 9. The motor according to claim 1, wherein themotor includes a temperature calculation unit for calculating a rotortemperature and/or a temperature of a magnet embedded in the rotoraccording to an oil temperature detected by the temperature detectionsensor.